Methods of forming a carbon fiber reinforced carbon foam are provided. Such a method may comprise heating a porous body composed of a solid material comprising covalently bound carbon atoms and heteroatoms and having a surface defining pores distributed throughout the solid material, in the presence of an added source of gaseous hydrocarbons. The heating generates free radicals in the porous body from the heteroatoms and induces reactions between the free radicals and the gaseous hydrocarbons to form covalently bound carbon nanofibers extending from the surface of the solid material and a network of entangled carbon microfibers within the pores the porous body, thereby forming a carbon fiber reinforced carbon foam. Carbon fiber reinforced carbon foams and ballistic barriers incorporating the foams are also provided.

Geopolymer cement slurries, cured geopolymer cements, and methods of making cured geopolymer cement and methods of using geopolymer cement slurries are provided. The geopolymer cement slurry comprises cement precursor material, Saudi Arabian volcanic ash, and an aqueous solution. The Saudi Arabian volcanic ash comprises SO.sub.3, CaO, SiO.sub.2, Al.sub.2O.sub.3, Fe.sub.2O.sub.3, MgO, and K.sub.2O.

A system and a method for concrete production is disclosed. In some implementations, the method comprises the steps of mixing of a calcium carbide residue (CCR) and ordinary Portland cement (OPC) to produce a CCR-OPC blended concrete, incorporating the CCR-OPC blended concrete in its fresh or hardened state to a carbonation chamber for accelerated carbonation curing, and producing a carbonated CCR-OPC blended concrete after the accelerated carbonation curing. The CCR-OPC blended concrete is exposed to a carbon dioxide (CO.sub.2) gas to promote a plurality of properties. The system includes a blending module and a carbonation chamber. The blending module mixes CCR and OPC to produce a CCR-OPC blended concrete, and the carbonation chamber performs accelerated carbonation curing of the CCR-OPC blended concrete in its fresh or semi-hardened state to produce a carbonated CCR-OPC blended concrete.

Functionalized polyacrylate polymer compositions for treating clay or clay bearing aggregates compositions are disclosed. Also disclosed are methods for preparing the functionalized polyacrylate polymer compositions, admixtures containing such polymers and methods for the mitigation of clays in cementitious and aggregate compositions using these polymers.

A method for the preparation of industrial-scale concrete installations with improved compression strength, curling, shrinking and cracking characteristics, the method comprising the addition of nanosilica particulate, and more preferably, colloidal amorphous silica, having specific size and surface area characteristics, to a concrete mix after water has been added to the mix and the mix has been agitated.

The present invention provides a crack repair material of a concrete vacuum tube segment using ultra-high performance concrete (UHPC) for a hyper-speed transportation system and a crack repairing method for the same capable of, in a case in which a vacuum tube segment of a hyper-speed transportation system, such as the Hyperloop, is manufactured using UHPC, repairing cracks formed in the UHPC vacuum tube segment easily and conveniently using a crack growth prevention material and a patch repair material and capable of immediately repairing cracks formed in the UHPC vacuum tube segment to secure airtightness so that operation of a vacuum pump is minimized and overload of the vacuum pump is prevented.

Trona-accelerated composition for backfilling trenches are described. The compositions consist of aggregate (e.g., sand), Portland cement, Trona, water and sometimes air. The compositions may have a compressive strength of between 10 psi and 100 psi after 4 hours, a compressive strength of between 75 psi and 500 psi after 28 days, and a penetration resistance of between 4.5 tsf and 200 tsf after 4 hours. Also disclosed are methods of filling a trench with fast-setting flowable fill.

Concrete that exhibits increased flexibility (i.e., low modulus of elasticity) and high compressive strength is described. High aspect ratio structures as may be formed of the concrete are described. Structures formed of the concrete can have the same high compressive strength as similar structures formed from a more conventional concrete but can be significantly more flexible, which can allow for better load distribution in the structure and associated assembly. The concrete includes a weathered granite as coarse aggregate. The materials can be particularly beneficial in forming concrete components of a rail infrastructure, such as railroad ties and slabs.

A method may include: defining engineering parameter of a proposed cement slurry, the engineering parameters comprising at least a compressive strength requirement, a density requirement, a storage time requirement, and a thickening time requirement; selecting, based at least in part on a model of compressive strength, a model of storage time, and the density requirement, at least a cement and mass fraction thereof, at least one supplementary cementitious material and mass fraction thereof, and a water and mass fraction thereof, such that a cement slurry formed from the cement, the at least one supplementary cementitious material, and the water meets the compressive strength requirement and the density requirement; selecting, based at least in part on a model of thickening time, an accelerator and mass fraction thereof; selecting, based at least in part on a model of activator thickening time, an activator and mass fraction thereof; and preparing a cement slurry comprising the cement and mass fraction thereof, the at least one supplementary cementitious material and mass fraction thereof, the water and mass fraction thereof, and the cement retarder and mass fraction thereof.

A geo-polymeric concrete and a process for preparing the geo-polymeric concrete is disclosed. The geo-polymeric concrete includes class F fly ash in a range from 10-20 wt %, of the design mix river sand in a range from 25-40 wt % of the design mix, a natural aggregate in a range from 15 to 40 wt % of the design mix, silica fume in a range from 1 to 2 wt % of class F fly ash, an alkaline activator solution and a superplasticizer in a range from 0.5 to 3 wt %. The materials used for preparing the superplasticizer are easily available in the market in abundance at a reasonable cost. The superplasticizer is economically viable and improves the workability of the geo-polymeric concrete. The presence of the superplasticizer does not affect the compressive strength of the geo-polymeric concrete.